Scientists at the Massachusetts Institute of Technology have analyzed alternative solvents to water that could be a suitable basis for the existence of life on other planets. According to the research published on the arXiv server, water is currently the only medium for the emergence of life.
Researchers are considering whether there are other molecules prevalent in the universe that could play the same role as water -- dissolving essential nutrients, making them available to living organisms. Such substances must meet four criteria: dissolve only some molecules (but not all), play an important role in metabolism, not degrade a wide range of complex organic molecules, and exist for billions of years.
It turns out that of all known solvents, water is the only substance that meets these conditions. Ammonia meets the first three conditions, but is easily destroyed by ultraviolet radiation. Also, where ammonia exists, water also exists.
Concentrated sulfuric acid also fulfills the three basic conditions, although it is not known whether it can support the presence of a diverse array of organic molecules.
As for another common potential solvent, carbon dioxide, scientists question whether its properties are suitable for supporting a complex metabolism. However, it reacts with many types of molecules, and scientists suggest that the properties of liquid CO2 deserve further study./BGNES